Counterflow liquid-gas contact apparatus



SePt- 6, 1955 A. E. BAILEY COUNTERF' LOW LIQUID-GAS CONTACT APPARATUS iled Sept. '7, 1949 2 Sheets-Sheet l INVENTQR sept. 6, 1955 A. E. BAILEY 2,717,202

COUNTERFLOW LIQUID-GAS CONTACT APPARATUS Filed, Sept. 7, 1949 2 Sheets-Sheet 2 LW A ORNEYS COUNTERFLOW LIQUID-GAS CONTACT APPARATUS Alton E. Bailey, Louisville, Ky., assignor, by mesne assignments, to National Cylinder Gas Company, Chicago, Ill., a corporation of Delaware Application September 7, 1949, Serial No. 114,335

12 Claims. (Cl. 23-283) This invention relates to liquid-gas contact apparatus and method, and the invention is more particularly concerned with apparatus and method for effecting counteriiow of the liquid and gas in a process which is continuously operable.

Various features of the invention and especially certain features of the apparatus are adaptable to processes for etfecting contact of liquids and gases of a wide variety of types and for a wide variety of purposes.

Eiecting contact between the liquid and gas while passing the two in countercurrent relation to each other in a continuously operating system has been subject to certain diiiieulties and disadvantages, notably those caused by short circuiting. By short circuiting is here meant flow of some liquid from the region of the inlet of the apparatus to the region of the outlet of the apparatus without undergoing adequate contact with the gas; and flow of some liquid from the region of the outlet to the region of the inlet, with the result that the liquid in the region of the inlet comprises an admixture of constituents which have been subjected to contact with the gas to different degrees.

It is because of the foregoing and other diiculties that continuous countercurrent liquid-gas contact apparatus has not been extensively utilized in certain fields Where such short circuiting would be particularly disadvantageous. Since the equipment and method of the invention are highly effective in minimizing short circuiting, the equipment and method of the invention are especially adapted to use in certain particular processes, and notably in the hydrogenation of fatty oils and fats. Because of the especial adaptability of the equipment and method to the hydrogenation of the fats and oils, the invention is hereinafter described with reference to such hydrogenap tion. It may also be mentioned that the term oil or oils is used to refer to any of the usual oils or fats employed in hydrogenation processes, for instance, cotton seed oils, soybean oil, lard, etc., as used in the preparation of food products of various kinds.

To consider certain of the advantages of the invention which are of especial utility in the hydrogenation'of oils, it is lirst noted that the hydrogenation reaction is elected by addition of hydrogen atoms to the molecule of the oil at points of unsaturation, i. e., at the places where double bonds occur in the structure of the molecule.

In the hydrogenation of a typical material, for instance, in the hydrogenation of lard, the lard will initially have an unsaturation of about 70, as measured by its iodine value. Thoroughgoing hydrogenation of this material will effect reduction of the unsaturation to a value of 5 or 6, as measured by the iodine value. It should further be kept in mind that the more highly unsaturated material is more readily oxidizable, and therefore subject to deterioration, and for this reason it is important in the preparation of most hydrogenated oils for use` in food products that the iodine value and thus the unsaturation be kept at a For purposes of further explanation of the invention, assume that lard (at elevated temperatures) is being passed in countercurrent relation to hydrogen gas,'for instance, in a vertically arranged column, with the lard introduced at the top andwithdrawn from the bottom, and the hydrogen introduced at the bottom, so as to bubble up through the downflowing lard. If any appreciable amount of lard ilows more or less directly from the region of the inlet to the region of the. outlet without being subjected to direct contact With the hydrogen gas, Y

the material withdrawn from the outlet will, of course, represent a mixture'of constituents having different degrees of unsaturation because of the fact that the different constituents were subjected toV different degrees of contact with the hydrogen. non uniform product and since the product would contain a constituent of high unsaturation, that constituent Awould be readily subject to oxidation with the result that the' entire batch of material would readily spoil. lThis is .one

major diiiculty which results from short circuiting. There is another important disadvantage which results from such short circuiting, as follows.

If the hydrogen introduced at the bottom of the' column and bubbling up through the material therein carries with it an appreciable quantity of thelard from the region of the lard outlet to the region of the inlet, then the material in the region of the inlet also constitutes an admixture of constituents of different degrees of unsaturation and this, in turn, impairs the efficiency of the hydrogenation reaction, rsince the major portion of hydrogen has already been used up in the reaction Vin regions closer to the hydrogen inlet. Eiliciency of a counterflow operaton of this kind requires that the quantity of gas present in the oil be greatest toward the oil outlet, where the unsaturation of the oil has already'been` extensively reduced. On the other hand, in the region of the oil inlet the presence of only a relatively small amount of the hydrogen in the oil willbe effective for hydrogenation purposes, since at this point the oil has relatively high Y.

unsaturation and many unsaturated molecules are readily available for reaction with the hydrogen.' Furthermore, the admixture of lard of low iodine value from near the outlet with lard of higher iodine value in upper portions of the column has the elect of reducing the average iodine value of lard in the column. This, in turn, lowers the overall reaction rate, inasmuch as the rate of reaction at any point is substantially proportional to the iodine value. For example, if the partially hydrogenated lard at a specified point in the column has an iodine value of 50, its reactivity with hydrogen is approximately twice as great as similar lard admixed with a suiiicient quantity of low iodine value lard to ing not only results in production of an inferior product,

but also decreases the efficiency ot the hydrogenating process.

The present invention is directed to the problems referred to above, and according to the invention, a continuous counterow liquid-gas contact apparatus and method are provided, the apparatus and method virtually eliminating short circuiting and also having other advantages, as will further appear.

Briefly, the short circuiting is prevented by establishing a plurality of substantially independent and vertically superimposed treatment zones in the reactor or column, and by effecting substantial separation of the hydrogen and oil at the point of flow of hydrogen upwardly from zone to zone.

ferring to the accompanying drawings, in Which-fy 2,117,202 Patented Sept. 6, 1955- This, of course, would result in a` Figure l is a somewhat schematic View of a column for use in eiecting counterllow liquid-gas contact together with certain piping connections associated with the 0011111111; t

2 is a vertnl Sectional View Of. a liquid-sas contact column according to the present` invention, this View being on an enlarged scale as compared with` Figure 1;

Figure 3 is a View taken as indicated by the line 3 3 on Figure 2; and

Figure 4 is a view illustrating certain parts of an agitatingimpeller used in the column of Figures l and 2.

'In the following description it is assumed that the apparatus ofthe inventionis being used in. the hydrogenation of an oil. In Figure l the hydrogenating equipment is indicated in general by the letter A. This comprises a` column4 having. an oil inlet S at the upper end and an oil/outlet 6. at' the lower end. 'Hydrogen may be introduced through the connections 7--7 near the bottom of the column, and a gasoutlet such as shown at d may also be provided at the top. Oil to be hydrogenated may be de.- liveredto the connection by a pump 9 delivering to the line, 1-0 which includes a heater 11. A hydrogenation catalyst may alsoy be introduced into the. line 10 Vas by a, pump'12.

Hydrogen gas may be supplied from line 13 to both of the inlet pipes 7 7. A connection 14 communicating with the gas Voutlet 8 through a valve. 15 is extended to a pump or compressor 16 for eilecting recirculation of hydrogen, if desired.

A valved vent a may also be connected with the gas outlet 8.

The system may also include a jacket for the column A as indicated at 17, this jacket having an inlet at i3 for heat transfer medium and an outlet at 19. ri`he outlet delivers through pipe 20 to a heat transfer device 2i from which line 22 extends to the inlet 18. In the case of hydrogenation, this system may be used for cooling the column A as will further appear.

The outlet line 23 is provided with a control valve 24 adaptedy to be automatically opened and closed, according to .the level of liquid in the treating column, a level respon-V sive controller 25 being connected with valve 24. as is indicated at 26.

Various features of operation of thesystern briefly described above will be considered more fully hereinafterl following` a more specific description of the treatment column itself, which is now4 given with reference toFigf` uresj2, 3 and 4.

The column comprises a cylindrical sheil27 having an end closure 2,8 at the bottom downwardly dished and with which the liquid outletv 6 is connected. At its upper end the cylinder 27 is closed by a plate 3i? and the liquid inlet 5 extends through this plate as doesalsothe gas outlet 8.

The jacket 17 surrounds the major portion of the column, and it will be noted that the inlet to the jacket shown at 18 communicates with the lower endofthe jacket space, and the outlet 19 cornmunicatesjwith the upper end of the jacket space. in the intermediate region of the jacket a cylindrical bafile 31 is provided` dividing the baille space into concentric annular chambers which intercommunicate at the upper and` lower edges of the baille. in this way circulation of theheat transfer medium in the jacket isprornoted. A jacketl level indicator may be provided asfshown at 3 2, The connections 25a and 25h shown as extending through the jacketinto the interior of the cylinder. 27 arethose with whichthe controller 25 (Figure'flf) areassociated.

In the interior-v fftheicolumn al vertical agitator orgina-v pellershaft 33 extends substantially throughtrut-,theheight` of the column, this shaft being adapted to be; drivenatits upper` end. Theishaft carriesa seriesof vertically spaced agitating impellersfi, 375,Y 36,I y37.and,Bti-one ofl thse being. Shawn-011;an'.enlargedmaletn-Riapre 4l f. tioning and spacing rods 45 there being four such rods as will appear from the transverse section of Figure 3i.

The outer edge of each-ofthe partitions39-43 is spaced somewhat from` the inner surface of the shell` 27 to provide a narrow passage between the partition and the shell wall for downward iowof the liquid from zone to zone in the column. For the purpose of maintaining the peripheral passage, and also for the purpose of facilitating insertion and removal of the parts lying within the shell 27;, each of the partitions 39 -/-33, is provided with a series of small rollers- 4.6 which are received in slots formed in the edge of they partition, the rollers being rotatable on pivots 47 which are fastened to the partition as by welding.

The rods 45 further serve to mount hood ringsli, 49, 5G, 51; and 5,2., each ofwhichA is provided with detlectoi:

"lleS-QOOPfaiiug with the. several impellers to set up a thorough agitating and; mixingy action, of a kind described more4 fully; below. J-.ust below each impeller SP1-38') conical baiilesrSeS., S6.. 5.7. and 5e are mounted onA the central shaft 33 in positionsrto cooperate with the generally conical. portions 4 4. of the partitions 39-43. These' coned baillesv 5,4-58, serve to form liquid,k traps as will furtherappear.

With respect tothe showing of Figures 2 and; 3j, it

pointedounthat the gas inletpipes 7 are positionedwith relation to rodsASl in the manner appearing in Figure 3.

iuFigurel 2y these inletpipes hai/.e beenrnoved to the plane, o f the gure merely for the sakeof convenient illustration.

A typical Operation. of the foregoing, equipment is; de,- scribed below in connection with the hydrogenation, of lard.

Rferring toFigure l, the lard. isintroduced into the system by the pumpl 9, and tofacilitate pumping the lard shouldinitiallybe warmed sufficiently tobecome oily or fluid, for instance, up to a temperature of about 150) ii". In the preheater 1.1 the temperature of, the lard is desirably raised to a point in the' range of. from BGG F. to

400,5 Ahydrogenation catalyst nis introduced through.Y the pumpV 12. This catalystmay advantageously be introduced asa slurry of powdered nickel with a filter aid such asdiatomaceouslearth. Such a slurry may contain about 25 lbs. ofI filter aid, 25 lbs. of Vpowdered nickel and 250 lbs. of lard. Sufficient of this slurry is introduced by the pump i2 tolprovide aconcentrationof nickel as. catalyst.

inthe oil movingthrough thehydrogenator of 0.05% to The mixture of lard andcatalyst.is,introduccdthrough the inlet connectionS and a level in the columnismaintained asindicatedat L, for instance, byl the controller 25 operatingthe outlenvalve 2d., During the course of the hydrogeiiation, the exothermic character of the reactiontends 'to raise the temperature in the treatment c olumn and the temperature, for, p roductionof hydrogenated lard or so-called lard ilakes is advantageously from about400 F. to.4 5t) F. Circulation of the coolingmedium in the` jacketjis effected in av manner` to maintain a temperature in about the range indicated,

For the purpose` of this illustrative example, it is assumed that pure hydrogen is being introduced through connections 7-7 and thatthe quantity thereof represents the theoretical'quantity required to hydrogenate the lard,

to the desired extent, for instancean extent of hydrogenationeffecting decrease of the iodine value ofthe lard from to-6. When operating in this way, no excess hydrogen-.or otherf gases need be discharged fromtheconnection S., although it will be understood-what, ifcertainV impurities are present, there may be s'orr'ie gases which should be vented from the top of the column.

As the hydrogen discharges from the inlet pipes 7, it is immediately drawn into the impeller 38 in the lowermost hydrogenation zone of the column, andivigorous agitation occurs.

Unreacted bubbles of the hydrogen will ultimately collect in the interior of the cone bafe parts 57vandA 44. Gradually a pocket of hydrogen is developed in this way and this depresses the level of the lard to the line indicated at x, i. e., to a level corresponding to the lower edge of the surrounding conical bafe element 57. At this time hydrogen will bubble out and upwardly in the zone above the partition 42, to be drawn into the impeller 57v and thoroughly mixed with the lard in the toroidal path of circulation set up by the impeller in association with the hood ring 51 with its baies 53.

This action is clearly indicated by the arrows and bubbles applied to the treatment zone between the partitions 41 and 42. Gradually hydrogen bubbles will leave this swirl and will collect in the next higher conical baffles, to be delivered to the next higher hydrogenation zone. This mixing and separation of hydrogen is successively repeated throughout all of the zones of the column.

From the foregoing, it will be noted that the conical bathe elements act as separators, serving to trap the liquid in the lower zone but pass the gas upwardly into the next higher zone. With the bale elements arranged as indicated, this separating action is highly effective and substantially eliminates the carrying of oil or other liquid partitions 39-43 inclusive, are located in zones which are relatively quiescent, and which-therefore will result in downward carrying of relatively little gas with the liquid.

The operation of the partitions, bales and ilow passages as above described, substantially eliminates short circuiting of liquid between the zones adjacent the liquid inlet and the liquid outlet.

In the hydrogenation, according to the invention, it is of advantage to provide uniform temperature conditions through the height of the treatment column. This uniformity of temperature is obtained by utilization of the jacket 17 with its interior baille 31. For purposes of hydrogenation, such a jacket would ordinarily be ernployed for cooling the column, it being noted that the hydrogenation reaction is exotherrnic and therefore requires withdrawing heat to avoid excessive temperature rise. For this purpose a material, such as ortho dichlorbenzene (for instance, the material known to the trade as Dowtherm E), may be used in the jacket, this mate-g 22. The temperature at which boiling occurs, which in` turn determines the temperature in the reactor, is controlled by varying the flow of cooling water to the condenser 21, to raise or lower the pressure of vapors of the cooling medium in the closed system consisting of the condenser 21, the jacket 17, and the interconnecting piping. It is understood, of course, that a subatmospheric pressure must be employed if it is desired to maintain a temperature below 350 F. and a superatmospheric pressure must be employed if it is desired to maintain a temperature above 350 F. It will be understood that when the equipment of the invention is employed for certain other liquid-gas contact processes, it may be desired to utilize the jacket 17 for purposes of heating, rather than cooling.

Another advantage of the equipment of the invention is the fact that, in the case of hydrogenation, impure hydrogen may-readily be utilized in effecting such hydrogenation. For example, the mixture of hydrogen and nitrogen (75% hydrogen and 25% nitrogen) which results from the dissociation of ammonia may readily be utilized in the equipment of the invention for the purpose of hydrogenating oils and fats. In this case the nitrogen would, of course, be continuously discharged from the vent connection 8-15a. When the equipment is used as just mentioned, the hydrogenation is automatically accompanied by separation and elimination of the nitrogen from the gas initially used, and this is of advantage since it is not necessary to eiect a separate preliminary separation. In using impure hydrogen the principle of countercurrent ow of gas and oil embodied 'in the invention is particularly advantageous, since it permits fresh gas which is high in hydrogen content and highly reactive to come into contact with the oil that is relatively saturated and relatively non-reactive, whereas the gas which is impoverished of hydrogen and therefore relatively non-reactive comes into contact with relatively unsaturated and relatively reactive oil.

In the case of either hydrogenation or certain other types of liquidgas contact processes, the gas may be recirculated through the connection 14.

With regard to the jacket 17, it should be kept in mind that, while this arrangement is of especialradvantage for the purpose of cooling the column during hydrogenation of fats and fatty oils, when the equipment is used in various other liquid-gas contact processes, this jacket may be used either for cooling or heating purposes. The baiile arrangement in the jacket is particularly eiective to maintain substantially uniform temperature conditions lengthwise in the column in the diiferent treatment zones.

I claim:

1. In a liquid-gas contact apparatus comprising an upright column adapted to be substantially filled with a liquid to a level near the top thereof, a plurality of ver tically spaced partitions disposed in the column below the liquid level and dividing the liquid space of-the column into a plurality of substantially independent superimposed treatment chambers, an inlet for liquid com-V municating with an upper chamber, an inlet for gas communicating with a lower chamber, the partitions between adjacent chambers each including a pair of partition wall elements overlapped but spaced to provide a gas passage in an interior region of the column for upward flow of gas from chamber to chamber, said wall elements having free edges one of which is presented upwardly and the other of whichis presented downwardly, the upwardly presented edge being positioned at a level above the downwardly presented edge and arranged to form a liquid trap, and a liquid delivery passage disposed radially outwardly from said interior gas passage for downward iiow of liquid from chamber to chamber.

' 2. A construction according to claim l and further including an agitating impeller disposed in an upper chamber in the region just above said gas passage to receive gas rising therefrom and disperse the same in the liquid in said upper chamber.

3. Liquid-gas contact apparatus comprising an upright treating vessel having at least two substantially independent superimposed treatment chambers therein, an inlet for liquid communicating with an upper chamber, an inlet for gas communicating with a lower chamber, an upright rotatable shaft located in the interior of the vesseland carrying agitating impellers in said chambers, the chambers being separated from each other by a partition wall extending inwardly from the sides of the vessel and having an aperture with an upwardly directed edge portion surrounding and spaced from said shaft, a baflie wall element below the impeller in the upper chamber extending outwardly from said shaft and having a downwardly directed edge portion surrounding and overlapping the upwardly directed edge portion of said partition wall to provide a passage for upward delivery of gas from one chamber to another and to provide a liquid trap, and a passage for delivering liquid downwardly from one chamber to another, the liquid passage interconnecting said chambers adjacent the periphery of the vessel.

4. A construction according to claim 3 in which said bale wall element is connected to rotate with the impeller shaft.

5. Equipment for effecting liquid-gas contact comprising an upright shell, an upright impeller shaft arranged generally centrally of the shell, upwardly dished generally horizontal partitions in the shell dividing the shell space into a plurality of liquid-gas contact chambers, each partition having an oversized central aperture to pass the impeller shaft and providing annular passages around, the shaft interconnecting the chambers, a plurality of agitating impellers mounted on the shaft located in different chambers, annular baille wall elements also mounted on the impeller shaft below the impeller in the several chambers and cooperating with the centrally apertured portions of the partitions to form liquid traps restricting upward ow of liquid through said passages while providing free upward ow of gas from chamber to chamber, a liquid inlet communicating with an upper chamber, passages disposed radially outwardly from said central passage for downward flow of liquid from chamber to chamber, a liquid outlet communicating with a lower chamber, and a gas inlet communicating with a lower chamber.

6. A construction according to claim 5 and further including deflector rings peripherally associated with the agitating impeller and promoting toroidal circulation of liquid in the chambers in paths above and surrounding the annular balile wall elements mounted on the shaft in proximity to the zone of upward gas flow thereby providing for thorough dispersal of the gas entering such chambers.

7. A construction according to claim 6 in which the passages for downward flow of liquid from upper to lower chambers communicate with the upper chambers toward the bottom thereof radially outwardly of the paths of toroidal circulation.

S. Equipment for eecting liquid-gas Contact comprising an upright shell adapted to be filled with a liquid to a level near the top thereof, partition structures dividing the shell into a plurality of superimposed chambers, a liquid inlet communicating with an upper chamber, a gas inlet communicating with a lower chamber, the partition structures including nested but spaced conical partition wall elements arranged to provide passages disposed generally axially of the shell for gas flow upwardly vfrom chamber to chamber while acting as traps as against upward liow of liquid from chamber to chamber, a partition wall element of each partition structure having an edge portion extended close to the inside wall of the shell but spaced therefrom, and spacing means cooperating with said edge portion and the inside surface of the shell wall providing a passage between said edge portion and said inside surface for downward liquid movement, said spacing means being connected with the partition structure and being removable therewith axially of thc shell.

9. Apparatus for effecting countercurrent contact of liquid and gas comprising a vertically elongated vessel adapted to be substantially lled with a continuous column of liquid to a level near the top thereof, an inlet for gas and an outlet for liquid communicating with the interior of the vessel near the lower end thereof, an outlet for gas and an inlet for liquid communicating with the interior of the vessel near its upper end, and a plurality of vertically spaced transverse partitions disposed in the vessel below the liquid level, said partitions dividing the interior of the vessel into a plurality of superimposed liquid-gas contacting sections, each of said partitions including a partition element having a central aperture therein for upward movement of gas from each contacting section to the next higher contacting section and a baffle member disposed adjacent and above the opening in the partition element, said partition element having Asubstantially its CII entire outer edge spaced from the inner wall surface of the vessel to provide a passage adjacent the wall of said vessel for downward movement of liquid from an upper contacting section to the next lower contacting section in the vessel, said partition element also having an upwardly extending portion surrounding the central aperture therein, said baflle member having a downwardly extending portion overlapping in radially outwardly spaced relationship the upwardly extending portion of the partition element and extending downwardly to a level below the upper edge of the aperture in the partition` to define a passage for movement of gas into the contacting section above said partition element.

10. Apparatus for electing countercurrent contact of liquid and gas comprising a vertically elongated vessel adapted to be substantially lled with a continuous column of liquid to a level near the top thereof, an inlet for gas and an outlet for liquid communicating with the interior of the vessel near the lower end thereof, an outlet for gas and an inlet for liquid communicating with the interior of the vessel near its upper end, and a plurality of vertically spaced transverse partitions disposed in the vessel below the liquid level, said partitions dividing the interior of the vessel into a plurality of superimposed liquid-gas contacting sections, each of said partitions including a partition element having a central aperture therein for upward movement of gas from each contacting section to the next higher contacting section and a baflie member disposed adjacent and above the opening in the partition element, said partition element having substantially its entire outer edge spaced from the inner wall surface of the vessel to provide a passage adjacent the wall of said vessel for downward movement of liquid from an upper contacting section to the next lower contacting section in the` vessel, said partition element having also an upwardly extending portion surrounding the central aperture therein, said bafe member having a downwardly extending portion overlapping, in radially outwardly spaced relationship, the upwardly extending portion of the partition element and extending downwardly to a level below the upper edge of the aperture in the partition to define a peripheral passage for movement of gas into the contacting section above said partition element, and wherein the portion of the passage for the upward movement of gas which opens into the contacting section above the partition element is positioned at a higher level within the column than the opening to the portion of the passage for the downward movement of liquid to the contacting section below the partition element.

1l. Equipment for effecting liquid-gas contact comprising an upright shell adapted to be substantially lled with a liquid to a level near the top thereof, partitions dividing the shell into a plurality of superimposed chambers, a liquid inlet communicating with an upper chamber, passages for downward liquid flow from chamber to chamber, a liquid outlet communicating with a lower chamber, a gas inlet communicating with a lower chamber, passages for upward gas flow from chamber to chamber, liquid traps at theseveral gas passages prof viding against appreciable upward ow of liquid through the Vgas passage and wherein, as to the liquid and gas passagesV interconnecting a given pair of adjacent chambers the discharge opening of the passage for downward liquid ow is laterally spaced from the inlet opening of the passage for upward gas flow, and wherein said liquid passage discharge opening is at a lower level than saidY inlet opening of the gas passage.

l2. Equipment for effecting liquid-gas contact comprising an upright shell adapted to be substantially filled with a liquid to a level near the top thereof, partitions dividing the shell into a plurality of superimposed chambers, a liquid inlet communicating with an upper chamber, passages for downward liquid flow from chamber to chamber, a liquid outlet communicating with a lower chamber, a gas inlet communicating with a lower cham-y ber, passages for upward gas ow from chamber to chamber, liquid traps at the several gas passages pro* viding against appreciable upward flow of liquid through the gas passage, as to the liquid and gas passages interconnecting a given pair of adjacent chambers the .discharge opening of the passage for downward liquid flow is laterally spaced from the inlet opening of the passage for upward gas ow, and wherein said liquid passage discharge opening is at a lower level than said inlet opening of the gas passage, and a heat transfer jacket surrounding the shell and having a bale wall therein di viding the jacket space into an inner peripheral chamber and an outer peripheral chamber intercommunicating at both the upper and lower ends thereof to provide for circulation of a heat transfer medium.

References Cited in the flle of this patent UNITED STATES PATENTS 935,501 Hersey er a1. sept. 2s, 1909 10 MacNish Apr. 16, Allbright f Jan. 24, Hargreaves June 9, Schoneburn Mar. 6, Huff Mar. 5, Othmer May 7, Morlock Oct. 25, de Becze Apr. 11, Guthrie Jan. 19, Ziels May 3, Mills et a1. Aug. 29,

FOREIGN VPATENTS Great Britain Sept. 10, 

1. IN A LIQUID-GAS CONTACT APPARATUS COMPRISING AN UPRIGHT COLUMN ADAPTED TO BE SUBSTANTIALLY FILLED WITH A LIQUID TO A LEVEL NEAR THE TOP THEREOF, A PLURALITY OF VERTICALLY SPACED PARTITIONS DISPOSED IN THE COLUMN BELOW THE LIQUID LEVEL AND DIVIDING THE LIQUID SPACE OF THE COLUMN INTO A PLURALITY OF SUBSTANTIALLY INDEPENDENT SUPERIMPOSED TREATMENT CHAMBERS, AN INLET FOR LIQUID COMMUNICATING WITH AN UPPER CHAMBER, AN INLET FOR GAS COMMUNICATING WITH A LOWER CHAMBER, THE PARTITIONS BETWEEN ADJACENT CHAMBERS EACH INCLUDING A PAIR OF PARTITION WALL ELEMENTS OVERLAPPED BUT SPACED TO PROVIDE A GAS PASSAGE IN AN INTERIOR REGION OF THE COLUMN FOR UPWARD FLOW OF GAS FROM CHAMBER TO CHAMBER, SAID WALL ELEMENTS HAVING FREE EDGES ONE OF WHICH IS PRESENTED UPWARDLY AND THE OTHER OF WHICH IS PRESENTED DOWNWARDLY, THE UPWARDLY PRESENTED EDGE BEING POSITIONED AT A LEVEL ABOVE THE TRAP, AND A LIQUID DELIVERY PASSAGE DISPOSED RADIALLY OUTWARDLY FROM SAID INTERIOR GAS PASSAGE FOR DOWNWARDLY FLOW OF LIQUID FROM CHAMBER TO CHAMBER. 